Cinematography provides a means of entertainment, education, and cultural preservation. Perceived primarily as a recreational pastime to some, movies often play an important role in the cultural and economic fabric of our society. Today, the motion picture industry comprises a multi-billion dollar market that affects all of us.
A successful cinema production typically depends on many factors besides the receipts from a theatrical release. One critical element is the widespread distribution of the production while public interest remains relatively high. This typically involves releasing the motion picture in a variety of viewable formats for the home viewing market. Popular formats often include magnetic videotape and optical videodiscs. Moreover, taped reproductions usually take place for televised home viewing through subscriber services and the like.
While the public interest in recently released films is of critical importance in the motion picture industry, a heightened awareness has emerged for preserving historical images from the past. Cinema archives include thousands of decades-old original prints. Many of these films remain unseen by current generations. More importantly, however, because the materials used in early motion picture cinematography have a relatively short life span, it is believed that many of the original prints of such films will be lost forever unless the images are transferred to secondary media. Endeavoring to satisfy the public's craving for "home theater," those skilled in the art have devised image transfer systems for recording images from motion picture film to secondary analog and digital data formats. Commonly referred to as "telecine" and "scanner" machines, these systems provide a relatively high quality reproduction of the film consistent with conventional format standards.
Conventional telecine machines typically operate at real-time speed to generate a videotaped reproduction of a motion picture originally recorded on film. The machine generally includes a film transport mechanism comprising respective supply and take-up reels, a gate mechanism, and a video camera. The reels cooperate to drive the film at a constant real-time rate continuously across a substantially transparent film support. The support typically mounts within the gate mechanism and includes a flat transfer stage disposed perpendicular to the image axis of the video camera aperture and positioned opposite a lamphouse. To ensure at least a relatively consistent, albeit approximate lateral registration of the film with the camera aperture, the support often generally includes an edge guiding means. As the film winds through the gate, and across the transfer stage, the video camera continuously records the resulting projected image.
While conventional telecine machines work well for their intended applications, modern special effects requiring a combination of two or more separate scenes into a single scene typically need more accurate registration of the film relative to the camera recording field. Such registration preserves the illusion created by combining the two scenes. Successfully accomplishing these steps in conventional telecine machines often requires substantial time and effort to manually position, align and verify the film registration. Such effort correspondingly affects the videotape distribution schedule.
For creating digital recordings of motion picture film, scanning machines are typically utilized. Conventional scanning systems incorporate many of the same components as telecine machines, but replace the videotape recorder with a digital scanner to record each individual frame. Scanning machines often include a sprocket or capstan-like device disposed in the gate to sequentially engage the film perforations and slowly draw the film through the image stage for scanning. Respective frames are registered in position by a relatively large mechanical pin registration mechanism that is mechanically connected to the sprocket. The pins are aligned such that, during operation, the registration mechanism drives the pins into immovable engagement with perforations disposed a distance away from the frame to be registered. Often, the distance comprises several frames, introducing potential registration inaccuracies based on multiplied tolerance imperfections alone.
Because of the large amount of memory required to digitize each frame of the film in the conventional digital format, two or more videodiscs are often needed to record a single motion picture. To minimize this problem, an alternative format for transferring motion picture film into digital format focuses on image changes to identify recordable subject matter. Rather than recording image data from each respective frame, only sensed changes from previously recorded images are processed through implementation of a compression algorithm. This algorithm, known in the industry as Motion Picture Experts Group-2, or "MPEG-2", reduces the memory required to digitally process the film and enables end recording of an entire motion picture on a single digital videodisc. While conventional scanner machines perform adequately for their intended purposes, the lack of a driver to effect multiple modes of operation substantially hinders the efficiency of the associated film transport mechanism. Moreover, because the driver used in the scanner pin registration mechanism is mechanically coupled to the sprocket or capstan, significant response delays often occur during intermittent operation.
Therefore, those skilled in the art have recognized the need for a film transport and method for use with telecine and scanner systems to sequentially register motion picture film frames sequentially in precise relative position with respect to the recording field and effect optimal image transfer in accordance with one or more selectable modes of operation. The film transport and method of the present invention satisfies these needs.